A sample can be anything that can be observed or experimented on; it is basicall

Question

A sample can be anything that can be observed or experimented on; it is basically a part of a whole. For example; instead of using all drug users for a specific experiment, a researcher may only choose to use a small portion of the drug using population.

When selecting a sample, there are two general approaches; probability and nonprobability sampling. With probability sampling, all elements (e.g., persons, households) in the population have some opportunity of being included in the sample. With nonprobability sampling, population elements are selected based on their availability (because they volunteered) or because of the researcher's personal judgment that they are representative. The consequence is that an unknown portion of the population is excluded (those who did not volunteer). One of the most common types of nonprobability sample is called a convenience sample – not because such samples are necessarily easy to recruit, but because the researcher uses whatever individuals are available rather than selecting from the entire population. (Etext, 224)

Please give another example class.

Class,

What is a sample?  How do you go about selecting one?

Explanation / Answer

A sample is a smaller, manageable version of a larger group. It is a subset containing the characteristics of a larger population. Samples are used in statistical testing when population sizes are too large for the test to include all possible members or observations. A sample should represent the whole population and not reflect bias toward a specific attribute. Stratified sampling- Use it when there are smaller sub-groups that are to be investigated. Use it when you want to achieve greater statistical significance in a smaller sample. Use it to reduce standard error. Examples;A high school student who is studying year-ten attitudes in the school uses registration tuition classes as strata and studies a random selection of students from each of these classes. In a company there are more men than women, but it is required to have each group equally represented. Two strata are thus created, of men and women, with an equal number in each. Quota sampling- For a particular analysis and valid results, you can determine the number of people you need to sample.In particular when you are studying a number of groups and when sub-groups are small, then you will need equivalent numbers to enable equivalent analysis and conclusions. Example;A researcher in the high street wants 100 opinions about a new style of cheese. She sets up a stall and canvasses passers-by until she has got 100 people to taste the cheese and complete the questionnaire.

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